What's the most efficient way to draw edges for an object?
A possible way to do this is to use the Wireframe modifier. To get the result you want, add 2 materials to your object (the first for the faces and the second for the wire edges). Set the Pass Index of the second material to 1 (or any other number different from 0, which is the default value for any new material):



Add the Wireframe modifier to your object, and make sure to unchek Replace Original and to set the correct material index in the Material Offset input:



The final render will be something like this: